As weekend bloggers were quick to spot after two judges deprived Labour MP Phil Woolas of his Oldham East seat for lying in campaign literature, the same accusation could be levelled against every Liberal Democrat MP who promised to vote against higher tuition fees for students before changing their coalition minds.

But would an election court rule in their favour, as they appear to have done in this case, because they sincerely meant it at the time, Labour MPs were asking around Westminster yesterday? Woolas, a former NUS president and immigration minister, is a political bruiser, not universally liked, whom some colleagues think got what he deserved at the election court – the first such expulsion for 99 years.

He was immediately dropped by his party, keen to assure voters that it acts speedily against miscreants who apparently lie to voters. Others are appalled at Woolas's treatment while the case is still in the courts. "It's Gordon Brown's fault, he thought if we appeased voters they'd be grateful," explains one ex-minister.

Unease is enhanced by the knowledge that dirty politics in three-way marginal seats are not confined to the West Pennines, especially where identity politics involving ethnic or religious minorities – Catholic and Jewish as well as Muslim and Hindu village factions – are involved.

Such smears occur within all parties when the campaign adrenaline flows. "If we are to apply tighter rules it would help if they were modernised and made clear. But the party with the most to worry about telling campaign lies over the past 20 years is the Lib Dems," snaps an ex-cabinet minister.

Simon Hughes, no less, won his byelection with a "Straight Choice" leaflet about a gay rival. Legal or not?

Regardless of the Woolas case, thoughtful MPs on all sides fear that the wider ramifications of Oldham East's defeated Lib Dem candidate, Elwyn Watkins, will cause enormous problems for politics and drag courts into decisions that should be left to voters: who should represent them in parliament.

"The verdict of 70,000 voters has been overturned by two judges," they say. MPs protested in the Commons yesterday.

The precedents are unhappy. It was parliament itself which tried to expel John Wilkes, the 18th century radical, and Charles Bradlaugh, the Victorian atheist. Voters backed both men as they did Tony Benn, twice re-elected when he tried to renounce his inherited peerage in 1961. An election court declared against him, but he too won in the end.

More recently the law and the Electoral Commission have been used to help codify party political donations and MPs' expenses, both with confused and corrosive results. Tory and Labour politicians say they rarely lodge "bad loser" legal complaints about misconduct by smaller rivals (Tory Gerry Malone was smashed in the Winchester byelection he provoked by challenging Mark Oaten's narrow 1997 win), but that underdog parties often do.

"When I stood in Oldham the Lib Dems tried to get all my campaign literature destroyed because I supposedly made false claims about Paddy Ashdown. But I faced them down," recalls a veteran Tory. The SNP launched the ruinous loans-for-honours inquiry against Labour, and the BNP has been busy fomenting expenses challenges.

Even Woolas's enemies concede that election law is defective because he cannot appeal on disputed facts, only on process. For MPs, fearful their hardhitting election flyers will be lawyered into bland oblivion, there is one glimmer of hope. In 1999 Newark MP Fiona Jones was convicted of election overspending and disqualified. But she won her appeal and the expected flood of copycat cases never happened.